1. Field of the Invention
The present invention relates to an air bag device installed in a vehicle.
2. Description of the Related Art
As a so-called side-impact air bag device which is provided on an inner side of a side wall of a vehicle body and detects pressure or the like applied from a lateral direction of the vehicle body to inflate a bag body toward an interior of the vehicle body, for example, there has been proposed the type of air bag device to be mounted on the vehicle body from a front pillar to a center pillar along a roof side.
Namely, as shown in FIG. 5, an air bag device 80 of this type includes a cover 84 whose longitudinal direction coincides with that of a vehicle body 82 (i.e., the direction indicated by arrow B in FIG. 5). The cover 84 is disposed adjacently to the vehicle body 82 from a front pillar 86 to a center pillar 88 along a roof side 90 and is provided to be expandable into a predetermined form due to internal pressure applied from an inner side of the cover 84. Further, as shown in FIG. 6, a bag body 92 in a folded state is accommodated within the cover 84. The bag body 92 is formed so that its longitudinal direction coincides with the longitudinal direction of vehicle body 82 (i.e., the direction indicated by arrow B in FIG. 6). When gas is blown off from a module 94 provided in the center pillar 88 into the bag body 92, the bag body 92 presses against the cover 84 from the inner side thereof while swelling so as to cause the cover 84 to expand, and the bag body 92 further inflates to expand toward the interior of the vehicle body 82 into a predetermined form (the state shown in FIG. 5).
On the other hand, the bag body 92 of the air bag device 80 is ordinarily provided with a plurality of tongue-shaped mounting portions 96. The plurality of mounting portions 96 are formed along the longitudinal direction of the bag body 92 at predetermined intervals and are provided to respectively project out of the cover 84 so as to be fixed by fitting parts (not shown) such as bolts to the front pillar 86, roof side 90, and center pillar 88. As a result, the air bag device 80 can be installed at a predetermined position on the vehicle body 82.
However, in the air bag device 80 mounted in the above-described manner, since the bag body 92 is held by only these mounting portions 96, it is difficult for tensile force F.sub.1 through F.sub.7 between the mounting portions 96, which is caused by the internal pressure of the bag body 92 when the bag body 92 inflates, to coincide with one another. As a result, the expanding progress of the bag body 92 (i.e., the progress of a change in the shape of the bag body 92 from a folded state to a completely expanded state) is different from a previously-set expanding progress, and there is a possibility that an undesirable state such as "slack" (the state indicated by the two-dot chain line in FIG. 5) is caused in the bag body 92 during expansion of the bag body 92 up to the completely expanded state.
In order to overcome the problem like the above, there can be considered methods: the number of mounting portions 96 may be increased; the bag body 92 may be uniformly fixed to the vehicle body 82 along the longitudinal direction thereof; and the like. However, in these methods, the number of fitting parts such as bolts increases and the number of processes for fixing the bag body 92 also increases, thereby resulting in increase in cost.
Further, in the air bag device 80, since the interval between the mounting portions 96, or the like changes in accordance with the shape of the vehicle body 82, component members such as the bag body 92 should be prepared independently for each of vehicle types, which becomes an impediment to a reduction in cost.